Flame quenching air shutter for gas burners



Aug. 1, 1967 J. A. MORSE FLAME QUENCHING AIR SHUTTER FOR GAS BURNEFIS Filed Aug. 16, 1966 INVENTOR.

E v 0 P Mwm T A H 5 United States Patent 3,333,620 FLAME QUENCHlNG AIR SHUTTER FOR GAS BURNERS James A. Morse, Cleveland Heights, Ohio, assignor to The Adams Manufacturing Company, Cleveland, Ohio Filed Aug. 16, 1966, Ser. No. 572,712 2 Claims. (Cl. 1581l8) This invention relates to a flash-back flame extinguisher for the fuel burners of gas fired furnaces.

Conducive to a better understanding of the invention it may be well to point out that when manufactured and mixed gasses, having high flame velocity, are burned in conventional gas-fired furnaces the main burner flame is likely to flash-back and continue to burn at the manifold orifice, when the gas flow is interrupted, until the residual gas in the manifold is consumed, which may take several minutes.

If the gas is turned on before the flash-back flame has burned itself out the raw gas will burn at the manifold orifice. This is a highly undesirable and dangerous condition.

The primary object of this invention, therefore, is to provide an air shutter, surrounding the manifold orifice, that will automatically quench any flash-back of the main burner flame when the flow of gas is interrupted, either manually or through thermostatically controlled means.

Another object is to provide a device, of the type stated, that will extinguish flash-back flame well within the 8 second time limit set by the Underwriters Laboratories standards for gas burners.

These and other objects of the invention will become apparent from a reading of the following specification and claims together with the accompanying drawing, wherein:

FIGURE 1 is a longitudinal sectional view of the manifold and gas and air mixing-bell area of a conventional gas burner, showing the flame quenching air shutter,

that is the subject of this invention, mounted on the manifold at the gas delivery, or metering, orifice thereof;

FIGURE 2 is a sectional view of the unmounted flame quenching air shutter;

FIGURE 3 is a side elevational view of the same; and,

FIGURE 4 is a left end view of the structure illustrated in FIGURE 3.

Referring more particularly to the drawing, there is seen in FIGURE 1 the flame quenching air shutter for gas burners, that is the subject of the invention, broadly indicated by reference numeral 10, as it appears threadedly mounted on the manifold of a conventional gas burner unit 11.

Reference numeral 29 indicates a duct which delivers the proper gas and air fuel mixture to the main flame area of the burner, not illustrated.

The duct 29 is flared at its rear end 14 to provide a conical air-bell 13, terminating in an open air intake yoke 12 which has a threaded bore through which the gas manifold 15 is mounted and held immovably in place by a lock nut 21.

The manifold 15 is connected to a thermostatically activated valve, not shown, which controls the delivery of gas to the manifold 15.

The manifold 15 is internally threaded at its forward end 17 to receive a gas metering plug 18 having a gas delivery orifice 19.

The diameter of the orifice 19 is calculated to deliver a volume of gas to provide a main flame in the burner that will yield a maximum heat of between 25,000 B.t.u. to 400,000 B.t.u.

Inasmuch as the diameter of the orifice 19 is fixed, plugs having orifices of suitable size may be substituted for one another to provide the desired maximum thermal output.

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The hollow air shutter 10, that is the subject of the invention, is substantially frusto-conical in configuration, as is most clearly seen in FIGURE 3.

The air shutter 10 is fabricated from metal of suitable gauge, and has a flat circular base 22, a conical side wall 23 extending forwardly therefrom, at approximately 30, and terminating in a flat circular forward end, or apex, 24.

The base end 22 has an internally threaded bore 26 centered therein, adapted to engage external threads 16 of the manifold 15, as seen in FIGURE 1.

A set screwretaining block 28 is welded to the inner face of the base 22, proximate the bore 26.

Reference numeral 27 indicates a set screw which is mounted in an axially inclined threaded bore which passes through both the base 22 and the block 28, as is seen most clearly in FIGURE 2.

A circular gas outlet opening 25, of substantially larger diameter than the manifold orifice 19, is centered in the apex wall 24, as is seen most clearly in FIGURE 4.

Eight 5 wide slots 30 are cut through the wall 23 of the air shutter 10.

The slots 30 are circumferentially spaced and extend axially of the conical wall 23, from the gas outlet opening 25, which they intersect, toward the base 22.

However, the slots 30 stop short of the base 22, as seen in FIGURES 2, 3 and 4. The length of each slot 30 is approximately twice the diameter of the gas outlet opening 25.

In other words, if the opening 25 is in diameter the length of the slots 30 should be approximately The so fabricated hollow air shutter 10 is mounted over the forward end of the manifold 15 with its gas discharge opening 25 located downstream of the manifold orifice 19, as seen in FIGURE 1.

The air shutter 10 is thenfree to be rotated longitudinally of the manifold 15, toward or away from the conical wall 14 of the air-bell 13, to provide the proper mixture of air and gas to produce a clear blue flame for the burner, as is well known to those skilled in the art. The air shutter 10 is then locked in place by means of the set screw 27 which is drawn up tightly against the outer surface of the manifold 15.

It will be seen, by again referring to FIGURE 1, that 'one of the slots 30 is positioned on the upper face of the conical wall 23. This is important to the operation of the flame quenching action, as will be explained hereinafter, and is the reason for the multiplicity of slots 30, which assures that one of them will be in approximately this vertical position, no matter at what point the rotation of the air shutter 10 is haulted.

When the gas flow in the manifold of the lighted burner is interrupted, by the action of its control valve, the main burner flame will flash back to the gas discharge opening 25, at the apex of the air shutter 10, from which it travels up the slot, or slots 30, on the uppermost surface of the conical wall 23, and goes out, well within the 8 second time limit set by the safety standards, since the slots provide an elongated burning surface that quickly consumes the residual gas in the manifold 15.

When the gas flow is re-established the gas will ignite, properly, at the burner end of the duct 29 and will not burn at the manifold orifice 19.

It will now be clear that there is provided a device which accomplishes the objectives heretofore set forth.

While the invention has been disclosed in its preferred form, it is to be understood that the specific embodiment thereof, as described and illustrated herein is not to be considered in a limited sense as there may be other forms or modifications of the invention which should also be construed to come within the scope of the appended claims.

I claim:

1. In combination with a fluid gas burner having a manifold, including a gas delivery orifice, contained within the air-mixing bell of the burner duct:

(-a) a hollow, frusto-conical, air shutter havinga gas discharge opening centered in its apex, mounted coaziially on the manifold, over the orifice thereof, with its gas discharge opening located downstream of the manifold orifice;

(b) saidair shutter beingtmovable longitudinally of the manifold, between adjusted positions, toward or away from the conical wall of the air-mixing bell;

(c) the air shutter also having a plurality of circumferentially spaced slots cut through the wall thereof which intersect its gas discharge opening and extend axially of the air shutter toward its base end, stopping short thereof.

2. A hollow air shutter, as in claim 1, wherein the base thereof has a set screw embedded therein engageable with the manifold to lock the shutter in adjusted positions longitudinally of the manifold.

References Cited UNITED STATES PATENTS 15 FREDERICK L. MATIESON, 1a., Primary Examiner;

H. B. RAMEY, Assistant Examiner. 

1. IN COMBINATION WITH A FLUID GAS BURNER HAVING A MANIFOLD, INCLUDING A GAS DELIVERY ORIFICE, CONTAINED WITHIN THE AIR-MIXING BELL OF THE BURNER DUCT: (A) A HOLLOW, FRUSTO-CONICAL, AIR SHUTTER HAVING A GAS DISCHARGE OPENING CENTERED IN ITS APEX, MOUNTED COAXIALLY ON THE MANIFOLD, OVER THE ORIFICE THEREOF, WITH ITS GAS DISCHARGE OPENING LOCATED DOWNSTREAM OF THE MANIFOLD ORIFICE; (B) SAID AIR SHUTTER BEING MOVABLE LONGITUDINALLY OF THE MANIFOLD, BETWEEN ADJUSTED POSITIONS, TOWARD OR AWAY FROM THE CONICAL WALL OF THE AIR-MIXING BELL; (C) THE AIR SHUTTER ALSO HAVING A PLURALITY OF CIRCUMFERENTIALLY SPACED SLOTS CUT THROUGH THE WALL THEREOF WHICH INTERSECT ITS GAS DISCHARGE OPENING AND EXTEND AXIALLY OF THE AIR SHUTTER TOWARD ITS BASE END, STOPPING SHORT THEREOF. 